<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>执行上下文</title>
</head>
<body>
<script>

function foo(m, n) {
  var a = 1;
  let b = 2;
  const c = 3;
  class A {}
  console.log(bar)
  function bar() {}
  return a + b + c + m + n;
}

foo(10, 20)

</script>
</body>
</html>